Link between saturated fat and heart disease comes into question

Date: Mar-18-2014A new review of published evidence challenges current guidelines that suggest in

order to reduce heart disease risk, people should generally restrict intake of saturated fats -

like those found in butter and dairy foods - in favor of unsaturated fats - such as in margarine

and sunflower oil.

The analysis, published in the journal Annals of Internal Medicine by an

international group led by a team at the UK's University of Cambridge, included 72 separate

studies on heart risk and intake of fatty acids.

They found no evidence to support guidelines that say people should restrict saturated fat

consumption to lower their risk of developing heart disease.

They also found insufficient evidence to support guidelines that advise eating more foods

containing polyunsaturated fats (such as omega-3 and omega-6) to reduce heart risk.

And when they dug into the detail of specific fatty acids (such as different types of omega-3), the researchers found their impact on heart risk varied even within the same family of fatty

acids.

Findings question current guidelines

The researchers say their findings call into question current guidelines that focus mainly on

saturated versus unsaturated fat amounts, as opposed to concentrating on the food sources of the

types of fatty acid.

The study was part-funded by the British Heart Foundation, whose associate medical director,

Prof. Jeremy Pearson, says:

"This analysis of existing data suggests there isn't enough evidence to say that a diet rich

in polyunsaturated fats but low in saturated fats reduces the risk of cardiovascular

disease."

Lead author Dr. Rajiv Chowdhury of the University of Cambridge, who describes the findings as

"interesting," says they could open new lines of enquiry that carefully question our current

dietary guidelines, and adds:

"Cardiovascular disease, in which the principal manifestation is coronary heart disease,

remains the single leading cause of death and disability worldwide. In 2008, more than 17

million people died from a cardiovascular cause globally. With so many affected by this illness,

it is critical to have appropriate prevention guidelines which are informed by the best

available scientific evidence."

Researchers pooled data from 72 separate studies

To arrive at their conclusions, Dr. Chowdhury and his colleagues pooled and re-analyzed data

from 72 separate studies that included over 600,000 participants in 18 different countries.

The studies had assessed total saturated fatty acid in two ways: one as a component in

participants' diet, and the other way was by measuring levels in the bloodstream.

The results of the pooled analysis showed that whether measured in the bloodstream or as a

component of diet, total saturated fatty acid was not linked to coronary disease risk.

The analysis also found no significant link between heart risk and intake of total

monounsaturated fatty acids, long-chain omega-3 and omega-6 polyunsaturated fatty acids.

Individual unsaturated fats have different effects on heart

risk

However, when they looked in more detail at bloodstream levels of individual subtypes of

polyunsaturated fatty acids, such as long-chain omega-3 and omega-6 fatty acids, the researchers

found they linked to heart risk differently.

For example, they found some evidence that bloodstream levels of eicosapentaenoic and

docosahexaenoic acids (two main types of long-chain omega-3 polyunsaturated fatty acids), and

arachidonic acid (an omega-6 fatty acid) are each linked to lower heart risk.

They also looked in detail at saturated fatty acids. Here, they found some weak links between

bloodstream levels of palmitic and stearic acids (predominantly found in palm oil and animal

fats, respectively) and heart disease, but blood levels of the dairy fat margaric acid appeared

to significantly reduce heart risk.

Lastly, when they looked at results of trials testing the effects of adding omega-3 and

omega-6 supplements to diets, they found no benefit in terms of reducing risk of coronary

disease.

Prof. Pearson says large-scale clinical studies are now needed before drawing firm conclusions on this new evidence. In the meantime he advises:

"Alongside taking any necessary medication, the best way to stay heart healthy is to stop

smoking, stay active, and ensure our whole diet is healthy - and this means considering not only

the fats in our diet but also our intake of salt, sugar and fruit and vegetables."

Medical News Today recently published an article on adopting a healthy lifestyle to reduce heart

risk. The article explains the difference between heart risk factors that cannot be changed

like genes, and those that can, and cites smoking, obesity, diet and exercise as the main

modifiable ones.

Written by Catharine Paddock PhD




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